1. Field of the Invention
The present invention relates to an ion implanter and a beam measurement apparatus.
2. Description of the Related Art
In a semiconductor manufacturing process, a process of implanting ions into a semiconductor wafer (hereinbelow also referred to as “ion implantation process”) is normally performed for the purpose of changing conductivity and changing a crystal structure of the semiconductor wafer. An apparatus used for the ion implantation process is referred to as an ion implanter, and the ion implanter has a function of generating ions by an ion source and forming an ion beam by accelerating the generated ions, and a function of transporting the ion beam to a vacuum processing chamber and irradiating a wafer inside the processing chamber with the ion beam.
In the ion implanter, for example, an ion source, a mass analysis magnet device, a beam scanner, a beam collimator, an angular energy filter, a wafer processing chamber and the like are disposed along a beamline and are configured to implant ions into a wafer that is a semiconductor substrate. The angular energy filter deflects the ion beam by the action of an electric field or a magnetic field and guides an ion beam having a desired energy value to the wafer. In addition, a faraday cup is disposed downstream of the angular energy filter such that an ion beam current value can be measured during the ion implantation into the wafer. A part of beam that is not implanted into the wafer is measured.
A photoresist layer for forming circuit patterns may be formed on a surface of a wafer to be processed, and a material constituting the photoresist layer may be decomposed by ion implantation, causing the generation of gas. The generated gas may lower the vacuum degree of a wafer processing chamber or a beamline and change a charge state of ion constituting a beam by interacting with an ion beam directed toward the wafer. When the charge state of ion is changed, an aspect of the interaction between a beam and an electric field or a magnetic field applied by an energy filter or the like may be changed and the beam may deviate from a trajectory assumed in the design. Since a beam component of a trajectory deviating from the trajectory directed toward the wafer may be a measurement target according to the arrangement of the faraday cup, a control of an ion implantation amount may be affected.